Environmental enrichment for laboratory animals reduces chronic stress, improves welfare, and produces better science. Understanding enrichment principles helps advocates and researchers implement effective programs.
Enrichment provision for laboratory animals addresses the gap between the barren housing environments typical of research facilities and the behavioral needs of the animals housed there. Mice in standard barren cages without nesting material show chronically elevated stress hormones, impaired immune function, and abnormal behaviors — all of which also affect the quality of research data derived from them. The alignment between welfare and scientific quality creates a compelling practical argument alongside the ethical one for comprehensive enrichment programs. Despite this evidence, enrichment implementation is inconsistent across institutions and species, with rodents receiving significantly less attention than primates despite representing the vast majority of animals used. Strengthening enrichment requirements and monitoring compliance is a high-impact welfare intervention.